An ad hoc network does not depend on any base station apparatus or wired network and is an autonomous distributed network including a terminal apparatus as a constituent element. In an ad hoc network, terminal apparatuses are equal to one another, and information exchange is carried out by implementing multi-hop networking. Routing methods for such ad hoc networks include a table driving method, an on-demand method, and a hybrid method. In a table driving method, each terminal apparatus holds a routing table storing the destination of a packet signal in relation with a next-hop destination. The terminal apparatus also determines the next-hop destination from the destination of a packet signal by referring to the routing table. The routing table is periodically updated by a control packet signal. Examples of a table driving method include DSDV (Destination Sequence Distance Vector), WRP (Wireless Routing Protocol), CGSR (Clusterhead Gateway Switch Routing), and OLSR (Optimized Link State Routing).
In an on-demand method, a terminal apparatus of information generation source finds a route to a destination when requesting the transfer of a packet signal. The terminal apparatus of information generation source learns a reverse route to the terminal apparatus of information generation source by transferring a packet signal for inquiry by using a flooding method, and a destination terminal apparatus that has received the packet signal for inquiry responds. Based on a route found in such a manner, a packet signal is transferred from a terminal apparatus of a generation source to a destination terminal apparatus. Examples of an on-demand method include AODV (Ad hoc On demand Distance Vector), DSR (Dynamic Source Routing), TORA (Temporally Ordered Routing Algorithm), RDMAR (Relative Distance Micro-discovery Ad hoc Routing Protocol), and ABR (Associativity-Based Routing). A hybrid method is a combination method of the table driving method and the on-demand method.
In an ad hoc network, a technique has been suggested for simplifying the settings of terminal apparatuses. A predetermined terminal apparatus retains communication setting information, and a tag is held over near an IC card reader/writer mounted on the terminal apparatus. As a result, by having noncontact communication with a tag, the IC card reader/writer transmits the communication setting information. By performing in reverse the above-stated procedure between the tag and an IC card reader/writer mounted on another terminal apparatus, the communication setting information is transmitted to the terminal apparatus.